anyregion changer did it for me on more than 1 wii. just don't do anything stupid and it is safe. you will still have all the pirate footprints in your wii so don't go sending it to nintendo and expect it to be claen. and if you have preloader, this will overwrite it.

what about using IOS downgrader and Custom IOS Downgrader v1.2 by wanni that's what I used to go back to 3.2E from 4.2E and 4.0E but you have to be carefull if you updated your boot2 cause it'll cause a brick